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A Second Life for the Electric Car Battery

By Jim Witkin April 27, 2011 8:17 amApril 27, 2011 8:17 am

Nissan, via Bloomberg NewsA lithium-ion battery being installed in a Nissan Leaf car at a factory in Yokosuka, Japan.

As I wrote in a recent Times article on electric car batteries, scientists are expecting big breakthroughs in battery technology over the next five years that will increase the range of electric cars while reducing their cost. But even with these advances, researchers acknowledge that any rechargeable battery will gradually lose its capacity to store energy after repeated cycles of charging and discharging.

Once storage capacity falls below a certain level, the battery can no longer provide the range that electric car owners will expect, according to Micky Bly, the executive director of global battery, electric vehicle and hybrid engineering at General Motors. For its new Chevy Volt, GM expects that level to be around 60 to 65 percent of the battery’s original capacity, he said in a telephone interview.

At the same time, with most of a battery’s useful life still intact, automakers anticipate that it could serve other, less demanding purposes than powering a few thousand pounds of car.

A number of projects and new ventures are already under way to explore second-life applications for lithium-ion batteries. G.M. has announced a cooperative agreement with ABB, an energy technology company. And Nissan has formed a joint venture called 4R Energy with the Sumitomo Corporation.

This month, researchers at the National Renewable Energy Laboratory, financed by the Department of Energy, announced their own initiative in this area, a collaboration with academic and industry partners.
From a technical perspective, a special area of focus for the laboratory’s research will be repurposing these batteries for Community Energy Storage systems on the electric utility grid, according to Jeremy Neubauer, a senior engineer in the lab’s energy storage group. If all goes as planned, in the smart grid of the future electric utilities would distribute thousands of these Community Energy Storage packs throughout the grid to help them manage power flow, especially during peak times or outages.

One pack would store 25 to 50 kilowatt hours of electricity, which could provide power for a few hours to four or five homes. Packs of this size would require stringing together two or three electric car batteries, and the compact size of these batteries lends itself to this purpose, Mr. Neubauer said. He also expects that using second-life batteries would be cheaper for the utilities than buying new ones.

But beyond the technical feasibility, what’s new about the lab’s research will be the focus on testing new financial and ownership models for the car batteries. Ahmad Pesaran, principal engineer on the lab’s study, said, “We want to prove the battery has value beyond its use in the car, and by creating business models, to realize this added value, ultimately lowering the cost of owning the car for the consumer.”

One model calls for various companies like the automaker, local utility or finance company to retain ownership of the battery and lease it to the car owner. In this way, the owner only pays for the portion of the battery used while it’s in the car.

The researchers will also try to determine the optimal point for replacing the battery in the car, Mr. Pesaran said. “So while there is so much focus on these batteries providing eight to 10 years of life in the car, we may discover it makes more sense to replace them every five years to provide the maximum value back to the car buyer,” he said.

While it’s still early days, with plenty of technical, financial and regulatory unknowns along the way, the laboratory expects that automakers will need to find a solution for used electric car batteries as more electric vehicles start to hit the roads each year. Environmental regulations will dictate reuse or recycling, but recycling will probably return the lowest value back to whoever owns the battery, Mr. Pesaran says.

The laboratory’s research project could conclude as early as October 2012. Then it will offer the findings to anyone who wants to further explore these various ownership models. “Our motivation is to get more electric vehicles and plug-in hybrids out on the road,” Mr. Neubauer said. “If using the tools that we develop reduces the cost of ownership of the vehicle, then the project will have been a success.”

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